HETEROLOGOUS GENE-EXPRESSION OF BOVINE PLASMIN IN LACTOCOCCUS-LACTIS

Heterologous production of bovine plasmin was studied in the industria lly relevant bacterium Lactococcus lactis. Two sets of lactococcal gen e expression signals were coupled to the region of the plasmin gene co ding for the serine protease domain. When the promoter region of the p rtP gene was used, plasmin was detected mainly intracellularly in stra in BPL25 by Western blot hybridization. The intracellular presence of plasmin led to physiological stress. Expression of the plasmin gene dr iven by the promoter and complete signal sequence of the lactococcal u sp45 gene resulted in efficient plasmin secretion in strain BPL420. Ce ll lysis was observed in strains producing plasmin fragments including the catalytic domain, but not in control strains, which only produced a non-catalytic region of plasmin. The plasmin produced was shown to be biologically active.